A Big Effing Einstein Deal

Just a quick note here as I’m on deadline for a piece on this stuff, but today we got the official announcement of the worst kept recent secret in physics. Here, via the Guardian, is the TL:DR version of what was said:

On 14 September 2015 at 9:50 GMT, the two detectors of the newly upgraded Laser Interferometer Gravitational Wave Observatory (LIGO) detected a signal.

It was unambiguously a gravitational wave signal because it matched the predictions from Einstein’s general theory of relativity almost precisely.

This is huge news, as it is, among other things, the latest and most elusive (so far) direct confirmation of Einstein’s General Theory of Relativity, a theory of gravity that describes what we feel as a force holding our feet to the floor is in fact the local warping of spacetime by matterenergy. (In the case of our feet and our floor — that warping is the dent in spacetime created by the mass of the earth.)

It is as well a triumph of virtuosity in observation and measurement. The detection of a gravity wave is a simply wondrous an act of human hands and mind. It is a joy to witness, at least for me.

4 Comments on “A Big Effing Einstein Deal”

Hi! I had just started reading The Hunt for Vulcan the day before this announcement. When you write more about the LIGO result, perhaps you could address the likelihood (i.e., your best educated guess!) that this observation is sound and that gravity waves really were detected. I’m thinking, of course, of the BICEP2 observations mentioned in your book, as well as other turned-out-to-be-erroneous-or-misinterpreted observations also described in the book. Thank you!

(Loved the book! A very interesting story written by someone who made it doubly very interesting. Also, you provided what I think is the most intuitive presentation of relativity that I have ever encountered. I think it might have had something to do with the fact that you discussed the history of the development of the two theories. First, Special Relativity and its limitations, and then General Relativity and how it broadened the scope of relativity. And all along the way, describing the blind alleys Einstein went down and the new mathematical systems he needed to learn. Thank you from a non-physicist!)

As for the LIGO discovery. I’d rate it’s chances much higher than the BICEP2 result, for several reasons. For one there were two detectors at widely separated locations that got the same signal w/in essentially the same instant. Second, this wasn’t the case of having to pull a faint signal out of an enormous amount of background information. The gravity wave detection, though of a tiny amplitude, was still very clearly above baseline. Third, the detection was well within the designed sensitivity of the experiment (which is sort of another way of saying reason 2) — to the point that if the kind of event that could generate such a wave occurs, the expectation is that this instrument would detect it. Given that there were pretty good reasons to expect such events, this detection doesn’t really come as a surprise. (That it occurred so soon after the upgraded experiment came on line is a bit of stunner, but not the fact that this machine would in fact detect a signal if one happend by.)

Finally, a couple of other bits of support: the neat match between GR simulations of black hole collission/mergers and the actual signal detected is hardly a confirmation, but it does map onto the notion that the signal is real is the most economical account of what happened at LIGO. Second, there are credible reports of more detections at weaker signal strength, and the best confirmation will be more data that’s in agreement with the initial event.

[…] Tom Levenson explains at the Inverse Square, the LIGO work is “direct confirmation of Einstein’s General Theory of Relativity, a theory of gravity that describes what we feel as a force holding our feet to the floor is in […]

[…] Tom Levenson explains at the Inverse Square, the LIGO work is “direct confirmation of Einstein’s General Theory of Relativity, a theory of gravity that describes what we feel as a force holding our feet to the floor is in […]